The present invention relates to a system for rewriting information stored in electronic control units mounted on a vehicle.
Conventionally, a technique for rewriting information stored in an Electronic Control Unit (ECU) mounted on a vehicle has been proposed. In Japanese Patent Publication Laid-Open (JP-A) No. 2008-143418, it is described that a user is informed of a normal completion or abnormal completion of rewriting data in a flash memory of an ECU by using an indicator lamp.
In recent vehicles, in order to variously control a vehicle with better accuracy, a plurality of electronic control units are mounted. In memories of these electronic control units, information such as programs and related data is stored such that the electronic control units implement various controls. The stored information needs to be rewritten, for example, for upgrading to a new version. Of course, such rewriting may need to be performed for not only one electronic control unit, but also a plurality of electronic control units.
According to a conventional technique, when rewriting is performed on a plurality of electronic control units, an external apparatus is connected to the vehicle to access each electronic control unit. It is required that the external apparatus examines a version of information currently stored in each electronic control unit so as to determine whether the information currently stored in each electronic control unit has been already rewritten or has not been yet rewritten. Furthermore, in order to update the stored information, it is required to download new information into the external apparatus and then rewrite the old information with the new information on each of the plurality of the electronic control units in turn.
In such rewriting work, it is difficult to check the progress, that is, check which information of which electronic control unit has been completely rewritten at the present time. If the progress becomes unknown, it is required to serially examine the contents of the memory of each electronic control unit and determine whether the rewriting has been completed or not. The above patent document discloses a technique for informing a user of whether rewriting ends in a normal completion or not, which relates to a single electronic control unit. In a plurality of electronic control units, such a technique does not enable a user to grasp the progress, that is, grasp which information of which electronic control unit has been completely rewritten at the present time.
Furthermore, the external apparatus is operated by a user. During rewriting, the user who operates the external apparatus may be changed to another user. Because grasping the progress of the rewriting work is difficult as described above, an unrewritten portion may occur due to a subsequent user operation after such a change of the user. If an unrewritten portion occurs, there is no way to inform a user of this.
Therefore, a technique is desired for, when information stored in a plurality of electronic control units is rewritten (updated), enabling a user to immediately grasp a progress of the rewriting such that the rewriting is completely performed on the plurality of electronic control units without causing an unrewritten portion.